Centralized traffic controlling system



Sept. 17, 1940. N. D. PRESTON CENTRALIZED TRAFFIC CONTROLLING SYSTEM 6 Sheets-Sheet 1 Filed Jan. 27, 1952 Hana HT E MQN mmL m v Illllllll'lllL rll-lll I ll lulllllll llllI m MM w uoEEo Sept. 17, 1940. N. D. PRESTON CENTRALIZED TRAFFIC CONTROLLING SYSTEM Filed Jan. 27, 1932 6 Sheets-Sheet 2 Sept. 17, 1 940.

6 Sheets-Sheet 3 I Filed Jan. 27, 1932 mam 1 2 MMM n nE m u .N 0 Q. 1 I Q m w u q m 3 E E T 1 T 2% T Q m 34 ms, 3 v n w Y. F Y 1413 m3 m2 S? iwwa SVILE m A an R2 A T m 3 NE a an mg 5 a. nu P T u w E mm" .3 mum TTL 1 N H 8 F mm 3 m mom w m mm m WEQ n 5 Pk? Em S q UEM fwd- ROEEOU EOEEO U .QNGE

6 Sheets-Sheet 4 Sept. 17, 1940. N. D. PRESTON CENTRALIZED TRAFFIC CONTROLLING SYSTEM Filed Jan. 27. 1932 u and wm :3 m: at N mm we a p 1940- N. D. PRESTON CENTHALIZED TRAFFIC CONTROLLING SYSTEM Filed Jan. 2'7, 1932 6 Sheets-Sheet 5 QNE ' INV'ENTOR Patented Sept. 17, 1940 UNITED STATES 2,215,436 CENTRALIZED TRAFFIC CONTROLLING TEM Neil D. Preston, Rochester, N. Y., assignor to General Railway Signal Company, Rochester, N. Y.

Application January 27, 1932, Serial No. 589,186

42 Claims.

This invention relates to a relay code-type selector system, which is more particularly adapt- 'ed for controlling the signals, and switch machines of a railway system, and for receiving indications as to the progress of trains, positions section of track, it becomes apparent that the number of line wires of the system should be reduced to a minimum and at the same time it should be possible to transmit the controls and indications at a sufiiciently high rate of speed to avoid the accumulation of stored controls and indications.

With the above and other important considerations in mind, the present invention contemplates the use of a very large variety of distinctive code characters, so that less steps need be taken to obtain the necessary number of distinctive code combinations required. In accordance with the present invention, it is proposed to use three line wires and to employ code creating and code deciphering relays, with the provision of means to condition each of two of these line wires with positive or negative polarity, or de-energize either 91' both line wires, as a result of which any one of nine difierent conditions may be impressed on the line circuits. For instance, if one of the line wires is called a line A and the other one is called a line B, while the third line wire is used as a common return for lines A and B, then with the line B deenergized, the'line A may be energized or resulting in two distinctive conditions; with the line A deenergized, the line B may be energized or thus giving two more distinctive conditions; and with the line A energized or the line B may be energized or giving four more distinctive conditions, thus resulting in eight distinctive conditions of these lines A and B used for forming code characters. thermore, with the line A and line B both deenergized, a ninth condition results, but this ninth condition is used for spacing the above mentioned code characters and for stepping purposes and does not constitute a distinctive code character for transmitting purposes. Obviously, the provision of eight distinctive code characters for each step means that sixty-four distinctive codes Fur-- may be obtained where each complete code comprises two steps; and similarly five hundred and twelve distinctive complete codes may be obtained where each complete code comprises three steps. Thus, one purpose of the present invention is to provide a code system which builds up very rapidly as the number of steps are increased, and to accomplish this over a minimum number of line wires.

One feature of the present invention. is to so organize the control line circuits with the apparatus at the central ofice and at the field stations that irrespectivev of Whether the control office is transmitting codes to a field station or whether a field station is transmitting codes to the central office, the same timing apparatus located only in the central office is effective to measure off the time duration of the impulses and the spaces between the impulses. In other words, the central ofiice or any one of the field stations may distinctively energize the line circuits as above pointed out to form eight distinctive code characters for each step, but irrespective of the location of the particular transmitting apparatus for a cycle of operation of the system, the timing of the steps is accomplished in the-central office.

This feature has beenshown in my later filed copending application Ser. No. 596,516, filed March 3, 1932, in which I am claiming all of the subject matter which is common with this application with regard to the above mentioned feature and its related elements.

Other objects and purposes oi the present invention reside in the provision of means whereby indication codes may be transmitted from one of a large number of field stations connectediin series to a central oifice through the medium of a source of current located at the most distan field station.

Another feature of the present invention resides in the provision of means whereby a cycle of operation may be a short cycle for transmitting either control impulses from the central ofiice to a particular way station, or maybe a short cycle for transmitting indication impulses from a particular way station to the central office; or a cycle of operation may be a long or tandem cycle, during which the first portion of the cycle transmits distinctive control impulses to a particular way station and during which the second portion of the cycle transmits distinctive indication impulses from the same or a different way station to the central oflice, there being no period of hesitation, or blank, between these two portions of the tandem cycle.

Other objects, purposes and characteristic features of the present invention reside in particular interconnections between associated relays to obtain new and peculiar functions which may be used in the other types of selector systems, and the like, which will be apparent from the accompanying drawings and will in part be more particularly pointed out in the description hereinafter.

In describing the invention in detail reference will be made to the accompanying drawings, in which:

Fig. 1 shows in a schematic manner the selector system embodying the present invention, with many of the details omitted for convenience;

Figs. 2A, 2B, 2C and 2D illustrate one embodiment of the invention in detail with some of the intermediate stations omitted; and

Fig. 3 shows the code tables for a particular control cycle, for an indication cycle and for a tandem cycle.

Structura-Jt is believed expedient to first name the various relays and point out briefly the functions that they perform. With the drawings of Fig. 2 arranged endto end it will be noted that the various way stations are connected by three line wireanamely, line A, line B and common which is the return wire for lines A and B, and that at the central oflice and at each way station line A and line B include a threeposition polar relay and that the various line relays may be energized from the central office battery l9 and that they also may be energized from any one of the way stations from the battery I I located in the end battery control station, this being most clearly shown in Figs. 1 and 2D of the drawings.

Referring again to Fig. 1 of the drawings, it will be noted that the control code selecting relays CSA and CSB are located in the central oflice and are used for determining the character of each combination of pulses on the line wires A and B, namely, or deenergized. Also, it will be noted that the office battery selecting relay OBS is normally deenergized so that it may through its contacts i9! and I92 connect the lines A and B to the central office battery through the contacts I46 and M! of the control selecting relays CSA and CSB, but when energized connects the lines A and B directly to the common return wire. Also, it should be noted that there is a field station battery selecting relay FBS located in the end battery control station at the extreme end of the system (see Figs. 1 and 2D), and that this station battery selecting relay FBS is normally deenergized and connects the three line wires together, but when energized connects the lines A and B to the battery I I, the mid-point of which is connected to the common return wire. Attention is now directed to the fact that if the relays OBS and FBS are both energized the polar line relays LA LB located in the central office CO may be operated to any one of their three distinctive positions in accordance with the condition of energization of the relays CAP, CBP, PAP and PBP at the particular way station where the station selecting and pulsing determining relay LIR is up (see Fig. 2C) The relays CAP and CBP may for convenience be called the continuity indication code pulsing relays; whereas the relays PAP and PBP may for convenience be called the polarity indication pulsing relays. It may be pointed out here that these relays CAP, CBP, PAP and PBP can be rendered effective only at one way station at one time, as determined by the lock-in relay LIR.

It will be noted that the various line relays have been designated LA with the proper exponent corresponding to the station in which it is located for those included in the A line, whereas they have been designated LB with the proper exponent when included in the B line. It will be noted that the various line relays are repeated, except for polarity, by repeater relays LAP and. LBP containing exponents corresponding to the way station at which they are located, and that these relays have included in series therewith a slow acting relay SR containing an exponent corresponding to the station at which it is located, but this slow acting repeater relay is not connected in series with the repeater relay of the B line, namely, LBP until the slow acting relay has first been picked up by the A line, the purpose of this feature is to maintain the slow acting repeater relay SR deenergized, this relay manifesting the normal condition of the system that the A line is deenergized and the B line is energized.

At the end battery control station, located at the far end of the system (see Figs. 1 and 2D), is an indication conditioning relay OT, which becomes energized in the event that an indication is to be transmitted, this irrespective of whether the indication is to be transmitted in a short indication cycle, or whether it is to be transmitted in the second portion of a tandem cycle, and also independently of whether the last or an intermediate station is ready to transmit an indication, and this indication conditioning relay OT is used to energize the field battery selecting relay FBS, the energization of this field battery selecting relay FBS taking place upon the first step of the cycle in the event the cycle is an indication cycle, but is energized on the fourth step of the cycle in the event the indication is to be transmitted during the second portion of a tandem cycle.

Referring now to Figs. 2A, 2B, 2C and 2D of the drawings, the stepping relays in the central ofiice have been designated a, b, o, f, g and h, whereas the companion way station stepping relays have been numbered I, 2, 3, 6, 1 and 8. It will be noted that the pick-up circuits for these various stepping relays include back contacts I3 and I4 at the central office and back contacts I5 and H5 at the way station of line repeating relays LAP and LBP and LAP and LBP respectively, from which it is apparent that stepping takes place only when both lines A and B are deenergized. The half-step relays HS and 1-18 are employed to keep the stepping relays from successively picking up in rapid sequence in response to the first deenergization of the lines A and B, as interpreted by closure of contacts l3, l4, l5, I5, of relays LAP", LBP, LAP and LBP respectively, it being understood that each stepping relay is to pick up upon deenergization of the lines A and B, and the contact ll of the half-step relay HS (see Fig. 2B) must be down for-all odd numbered stepping relays to pick up and must be up for all even numbered stepping relays to pick up, as is also true of contact 45 of relay H8 (see Fig. 2D)

Referring now to Fig, 2B the impulsing relay IM is the relay that determines the time when both lines are to be opened, that is places the double zero code on a line for the purpose of stepping the stepping relays in the central office and in the way stations in synchronism, and also determines when the new code character is to be transmitted, this by reclosure of the lines A and B. This relay IM carries out this function of opening and reclosing both lines A and B simultaneously, not only when the code originates in the central ofiice but also if the code originates at any one of the way stations, of which only one has been shown for convenience. In this connection it should be noted that the open condition of one of the lines A or B at a time is accomplished by the contacts of control there is a repeater slowacting relay SRP which i repeats the picking up and dropping of the relay SR after a short interval of time.

In the central oflice there is also a field starting relay FST and an office starting relay ST, controlled by code determining relay CD which is controlled by the lever change relay LCR the purpose of which is in part apparent and will be more particularly pointed out. hereinafter. Similarly, each field station is provided with a normallyenergized stick change relay CH (see Fig. 20), which relay CH is normally stuck up through contacts which are momentarily opened by a changed condition at such field station which is to be transmitted to the central ofiice. Each of the way stations is also provided with a relay SE, having an exponent corresponding to the way station, which is picked up if the line A is energized positively during the initiating period of the system, that is, the first changed condition of the lines after the normal period during which the line A is deenergized and the B line is energized with current of positive polarity. With this relay SE (with proper exponent) in the central ofiice and the various way stations picked up, a short indicating cycle is transmitted.

In order to interpret the character of the code not only for a particular step, but for a series of steps, there have been provided in the central office and in each of the way stations polarity code signifying relays A, A B and B which signify the polarity of the lines A and B respectively, during a particular selecting period, similar continuity code signifying relays M", M N and N are provided to signify whether the lines A or B are energized or deenergized during this selecting period. The purpose of these various relays A, B, M and N, containing proper expoe nents, is to integrate at particular times the condition of polarity and continuity of the lines-A and B, and they result in picking up the proper code relays SOI, SO2, KOI or KO--2, the numeral in these reference characters signifying the digit of the code, so to speak, this because one of these relays, there being eight of the first order, is picked up during the first step, and one of sixty-four code relays of the second order is picked up through a contact on a code relay of the first order during the second step of the cycle, and so on. From this consideration it is apparent that if code relays of two different orders are used, any one of sixty-four way stations may be selected, and that if code relays of the third true of the number of Way station registration relays that may be picked up in the central office from distant waystations. It may be pointed out here that the line repeater relays LAP, LBP, LAP and LBP and their associated slow acting relays are energized-through the contacts 9, I2, 92 and I I5 of relays LA, LB LA and LE respectively.

In the particular embodiment of the invention illustrated, it is assumed that two steps will be employed for selection of stations for the outbound transmission of controls from the control office, and one step for the transmission of such controls to the particular station selected. Similarly, two steps are used for station registration for in-bound indications, and one step for the transmission of the indications. These three steps provide a station capacity of 64, and 8 distinctive controlsor indications for each of these stations. The three stepping relays a, b, and c in the control ofiice (Fig. 2B) and the stepping relays l, 2, and 3 (Fig. 2D) at each field station, are used to provide the three steps for outbound station selection and transmission of controls. The three stepping relays f, g, and h in the control ofiice and 6, l, and ii at the field stations provide the steps for the in-bound trans-.

mission of indications. In other words, in accordance with this invention, the stepping relays for the transmission of controls are arranged in one group, and the stepping relays for the transmission of indications are arranged in another group; and provision is made, in the manner explained more in detail later, so that at the beginning of an operating cycle, the steppingmay start with the first group of stepping relays for the transmission of controls, or with the second group for the transmission of indications, de pending upon whether or not this operating cycle is to be for controls alone, or for indications alone. In the case that indications are ready to be transmitted at the same time the controls are to be transmitted, the stepping starts with the first group of stepping relays for the transmission of controls, and continues through the second group of stepping relays for the transmission of indications, during the same operating cycle,

OPERATION Generally speaking, in assuming the system to be at rest in the normal condition shown, the first phase of the operation involves starting the system into operation whenever new controls or new indications have to be transmitted, and determining whether or not the consequent operating cycle of the system shall be one for the transmission of controls alone, or indications alone or a tandem cycle of both controls and indications. During the initial energization of the line circuits, which may be called the conditioning or initiating period, the polarity of energization of the line A determines whether or not the consequent operating cycle shall involve the transmission of controls, either alone or followed by the transmission of indications in a tandem cycle.

Following this initial conditioning operation, the stepping takes place, during which the lines A and B are selectively energized with either may be.

polarity or deenergized to provide any one of 8 distinctive code impulses for each step, thereby selecting or registering the station, and transmitting the controls or indications, as the case At the end of this stepping operation, which may be either a single cycle of controls or indications, or a tandem cycle of both controls and indications, the system is restored to the normal condition, ready for another operating cycle.

Fig. 3 of the drawings shows typical examples of the way in which the lines A and B are respectively energized or deenergized for a control cycle, for indications, and a tandem cycle, a specific code call for a particular station, and a specific code combination for controls and indications being assumed. It should, of course, be understood that the number of steps illustrated and controls and indications assumed and described, are merely typical and representative of the functioning of the system of this invention. In particular, the following detail description of the operation has been limited to the selection or registration of only one particular station, and the transmission of only one kind of control or indication; and it should be understood, that the system operates to provide in a similar way for the selection or registration of a large number of stations,

and the transmission to or from each station of a large numb of controls and indications.

Referring to the code tables of Fig. 3, under normal conditions with the system at rest, or in the periodof blank, the line A is deenergized, as indicated by the symbol 0, and the line B is energized with positive polarity, as indicated by the symbol If new controls are ready to be transmitted prior to the initiation of an operating cycle, the line A is energized with anegative polarity, while the line B is held energized with the positive polarity for station lock-out purposes. If, however, no new controls are ready to be transmitted at the beginning of an operating cycle, initiated from the field, then the line A is energizedwith positive polarity, while the line B is held energized. These diflerent conditions of the line circuits during the initiating or conditioning period are shown in Fig. 3 for the control cycle and the indication cycle. In the case of an indication cycle, the condition of the line B is indicated by the symbol (0+), because the line B is energized only up to the nearest station ready to send in indications, and is deenergized beyond that station. If the line A is energized for a control cycle, the stepping starts with the first relays a and I of the group for controls; whereas if the line Ais energized with the stepping starts with the first relay 1 and 8 for the second group of stepping relays for the transmission of indications. If at the time an operating cycle is initiatedfor the transmission of controls, some field station has new indications to transmit, conditions are established so that two groups of stepping relays are operated, without restoring the system to normal, thereby providing a tandem cycle.

With this brief and general statement of the operating principles of the system, the operation will now be described in detail for certain typical controls and indications. Thus, the operation will be described for the case where the lever L in the control ofiilce is moved from the position shown for the purpose of operating the switch machine control relay SMR at the particular field station shown in Fig. 2D, and for the case where the presence of a train on the detector track circuit having the track relay TR, as shown in Fig. 2D, may be transmitted and indicated in the control office by lighting the lamp I. Following this explanation of the transmission of controls and indications separately, it may then be explained how these typical controls of a switch machine and indication of a track circuit may be transmitted during the same double or tandem cycle.

Cycle of controls alone Referring to Fig. 2A, and assuming the lever L to be typical of one of the various levers in the control office operated manually by the operator, upon movement of such lever to a new position, by the operation of a starting button, or equivalent means, a relay LCR is deenergized, this being accomplished in the arrangement shown by opening the stick circuit for this relay through its lower winding at the lever contacts. The relay LCR shown is representative of a series of similar relays associated with the groups of levers belonging to the several stations; and associated with each of these relays is a code determining relay, one of which designated CD for the lever L having been shown. These several code determining relays are electrically interlocked, in the manner shown, for example, in the application of W.-D. Hailes et a1., Ser. No. 526,674, filed March 31, 1931, for the purpose of permitting these code determining relays to be energized only one at a time ina predetermined sequence while the system is at rest. The details of the means for thus enabling controls to be transmitted to stations one at a time as the operator positions the levers to diiferent positions, while preferably employed with the system of this invention, is not material to its operation; and for simplicity, a detail illustration and explanation of this means will not be given.

With the code determining relay CD picked up, an energizing circuit, including a front contact 22 of the relay CD and a back contact 23 of the relay FST, is closed for the oflice starting relay 0ST. Picking up of the relay 0ST opens its interlocked contact 24, thereby preventing further picking up of the field starting relay FST during the same cycle. Picking up of the ofiice starting relay 0ST closes the following energizing circuit for the control selecting relay CSA:-beginning at the terminal of the central oflice split battery, back contact 26 of the slow repeater relay SRP, front contact 2'1 of the office starting relay 0ST, wire 4, back contacts 28, 29 and 30 of stepping relays a, b, and 0, wire 56, back contact 3| of the ofiice starting selecting relay OBS, through the winding of the control selecting relay CSA, to the common return wire C connected to the mid-point of said split battery. Negative energization of the relay CSA causes the line A to be energized by current of negative polarity (this picks up relay LAP but this relay performs no functionat this time), and since the line B is still energized with current of positive polarity the proper current is flowing during the initiating period of the system, namely negative current for line A and positive current for line B, to initiate the system for a control cycle (see table Fig. 3). When the line circuit A is thus energized with a negative polarity, the polar armature l8!) of the line relay LA in the control ofiice is assumed to move to the left; and while a circuit is closed is not energized, since its coil is connected to Similarly, the relays as SE at the several field stations are not energized. Consequently, the stepping starts with the first relays a and l of the group for transmission of controls.

The energization of the line A with either polarity "establishes a circuit through the contact finger 9 of the line relay LA for energizing the slow-release relay SE in series with the relay LAP; and after a short time, this slow-releasing relay SR. attracts its armature and closes its front contact id to energize the slow-releasing repeater relay SRP. Similarly, at each field station a slow-releasing relay such as SR is energized. These slow-releasing relays maintain their armatures attracted during the impulsing of the line circuits throughout the operating cycle.

The energization of the slow-releasing relay SR. in the control ofiflce breaks at its back contact 277 the pick-up circuit for the code determining relay CD leaving this relay held up by a stick circuit through its front contact l9, which is broken at the back contact 2! of the stepping relay 0. The relay LCR. is likewise restored to its energized condition on this last step in the particular simplified arrangement shown, it being assumed that this relay LCR. will pick up quicker than the relay CD will drop.

The energization of the slowreleasing repeater relay SRP in the control office marks the end of the conditioning or initiating. period, after which the system alternately deenergizes both lines A and B to take a step, and energizes the lines A or B, or A and B, with selected polarities to provide the code combinations of impulses for the selection of stations and transmission of controls, this stepping operation and transmission of controls being hereinafter explained more in detail.

Both lines A and B are opened after the conditioning period to take the first step by energizing the impulsing relay IM over a circuit through the front contact 36 of the slow-releasing repeater relay SRP, wire 3?, contact I05 of the relay HS in the lower position, lower winding of the relay IM and through the series of back contacts H3, H2, ill, I06, H19, 568, and Ill? of the stepping relays ac and Jh. The energization of the relay 1M opens both lines A and B at its back contacts 38 and 33. The deenergization of both lines A and B simultaneously, which in a sense may be said to be a zero-zero code, is the condition for stepping.

With the lines A and B both open, the line relays LA LA LE and LB all assume their pendent or deenergized positions, thereby causing deenergization of the line repeater relays LAP", LAP LBP and LBP thereby causing simultaneous closure of contacts of these relays, namely, contacts l3 and M in the central ofiice and contacts I5 and [6 at the way station (see Fig. 2C) and thereby resulting in the simultaneous completion of the following two circuits: ('1) beginning at the terminal front contact 44 of the relay SR back contact [3 of the relay LAP", back contact Hi of the relay LBP wire l8, back contact I! of the relay HS, back contacts M, 42 and 43 of relay h, f and b, respectively, winding of the relay a to the other terminal and (2) beginning at the terminal of a way station battery, (this circuit being present at each way station), front contact 35 of the relay SR back contact I 5 of relay LAP back contact 16 of relay LBP wire I26, back contact 45 of relay HS back contacts 48, ll and 48 of stepping relays 8, 6 and 2, respectively, at each of the way stations (see Fig. 2D, for example) through the winding of stepping relay 5 to the other terminal The relays a and I are then" stuck up through their respective stick circuits readily traced and including their respective stick contacts 44 and 49. The stepping relay i is thus conditioned to transmit the code condition of the next step to the various code signifying relays A B M and N Picking up of the stepping relay a breaks the circuit for the impulsing relay IM-at the back contact H3 of relay a, but since this relay IM is a neutral relay, and therefore slightly slow acting, it will not close its back contacts 38 and 39 until the control selecting relays CSA and CSB are energized to effect the next code character. The relay IM is thus the relay that determines the rate of stepping of the system. It should also be noted that for the particular code applicant'has picked to select the way station illustrated, only three code jumpers 513, 5! and 52 (see Fig. 2A) are employedthis because the second station selecting code character includes a zero code (see control cycle Fig. 3)

Bearing in mind that the code determining relay CD for the lever'L is energized, and noting that certain of the code determining jumpers 58, 5! and 52 have been placed in position to select a certain code, the control selecting relays CSA and CSB are energizedto one polarity or the other or deenergized, as the case may be,.

through the following circuits: (1) beginning at the terminal (See Fig. 2A), jumper 5!, front contact 53 of the code determining relay CD wire 54, front contact 28 of stepping relay a, back contacts 29 and 36 of stepping relays b and 0, Wire 56, back contact 3| of relay OBS through the winding of control selecting relay CSA, to common return wire C connected to the midpoint of the central ofiice battery, and (2) starting at the terminal of the central ofiice battery, jumper 52, front contact 58 of the relay CD wire 59, front contact fill of the steppingrelay (1, back contacts 64 and 62 of the stepping relays b and 0, wire 63, back contact 64 of the relay OBS, through the winding of the control selecting relay CSB, to the common return wire 0 connected to the mid-point of the central office battery. Relay IM now closes its'contacts 38 and 39. It is thus seen that the first station selecting code is for line A and for line B, as indicated in the control cycle column of Fig. 3 of the drawings.

Let us now observe what efiect this first station selecting code character has upon the apparatus shown in Fig. 2D ofthe drawings. With the line relays LA and LB (see Fig. 20) both energizedto-ward the left, and the contact 66 of relay LA toward the left, current of negative polarity is applied to the polarity code signifying relay A through the following circuit: be-

ginning at the terminal of a suitable field station battery, contact 66 of relay LA front contact 32 of the slow relay SR wire 5?, back contact 68 of the stepping relay 3, front contact 69 of the stepping relay I, through the winding of the relay A which is one of the two-position polar magnetic stick or stay-where-put type, thus energizing this relay toward the left. Simultaneously with this .energization of the relay A the relay B is energized to the left through the following circuit: beginning at the terminal of the way station battery, polar contact ill of:

the relay LB toward the left, wire II, back contact I2 of the stepping relay 3, front contact I3 of the stepping relay I, through the winding of the relay B thus operating this stay-where-put relay B to its left-hand position.

Also, with the lines A and B both energized the line repeater relays LAP and LBP are energized, so that the continuity code signifying relays M and N are energized as follows: (1) beginning at the terminal front contact I5 of the relay LAP front contact 76 of the relay LBP wire 'I'I, back contact I8 of the stepping relay 3, front contact I9 of the stepping relay I, through the winding of the relay M to the common return wire C connected to the midpoint of the way station split battery, and (2) beginning at the terminal front contact 80 of the relay LBP wire 8!, back contact 82 of the stepping relay 3, front contact 83 of the stepping relay I through the winding of the relay N to the common return wire C.

The relays A and B have thus been energized toward the left and the relays M and N have been energized toward the right, so that, with the relay HS now energized through front contact I56 of relay 5, and with contacts i5 and 76 of relays LAlE and LBP down, as will be the case when the relay IM is energized for the stepping relays to take their second step, the following circuit for the code relay SO-I is closedz-beginning at the terminal contact 85 of the relay N to the right, contact 86 of the relay M to the right, contact 87 of the relay B toward the left and contact 88 of the relay A to the left, code jumper 89, lowering winding of the relay SOI, front contact 983 of the stepping relay I, back contact 9| of the stepping relay 2, front contact 93 of the half-step relay BS wire 94, back contact I5 of'the relay LBP deenergized, and contact l5 of relay LAP deenergized, to the terminal The relay SOI isthus picked up during the next stepping period, namely when both lines A and B are deenergized. With code relay SO-I once picked up it is stuck up through its stick contact 5'1 and front contact 35 of relay SR in series. The code relay S()Iv has thus been picked up in response to the A, B code character transmitted during the first station selecting code.

We have already briefly mentioned the second stepping period, namely, the period with the line A and line B both deenergized, but let us now observe how this deenergization of the lines A and B took place. Referring to Fig. 23 it will be noted that the half-step relay HS was energized in response to the application of the A, B code character during the first station selecting code period, because of closed contacts 95 and 96 of line repeater relays LAP and LBP respectively, effecting closure of the following circuit:-beginning at the terminal front contact 91 of the stepping relay a, back contacts 98, 99, I00, NH and I02 of stepping relays b, c, f, g and h, respectively, upper winding of the relay HS", wire 94, through the contacts 95 and 95 in multiple, to the common return wire C. The closure of this circuit effected energization of the half-step relay HS, thereby closing its front contacts I03, I04 and 405. Closure of the contact IM caused the relay HS to be stuck up through a stick circuit including this contact I04 and the front contact 43 of the slow relay SR (see Fig. 2A), and lifting of the contact I closes the following circuit for the upper winding of the impulsing' relay IM to effect opening of the lines A and B: beginning at the terminal (+),back contacts I61, I08, I09, I05, III and H2 of relays h, g, f, SE", 0 and b, respectively, then through front contact II3 of stepping relay a through the upper winding of the impulsing relay IM, through front contact Il5 of relay HS", wire 31 and through front contact 33 of relay SRP to the other terminal thus resulting in the opening of the lines A and B for accomplishing the second stepping operation.

With the lines A and B now both deenergized, the second stepping period of the control cycle takes place, this occurring simultaneously with the integration of the code character resulting in picking up of the relay SO I, (see control cycle table Fig. 3) and the stepping relay b is picked up through the following circuit: beginning at the terminal front contact 44 of the relay SR (see Fig. 2A) back contacts I3 and 4 I4 of relays LAP and LBP, wire I8, front contact ll of half-step relay I-IS, back contacts I43, I44 and I45 of relays 9, SE and 0, front contact I I4 of the relay a, winding of the relay b, to,

With this relay b and through front contacts I22 and I23 in multiple of relays LAP and LBP beginning at the terminal of -way station battery (see Fig. front contact 35 of the relay SR (see Fig. 20), back contacts I5 and I6 of relays LAP and LBP wire I26, front contact 45 of relay H8 back contacts I21, I28 and I29 of relays I, SE and 3, respectively, front contact I of stepping relay I, winding of the stepping relay 2 to the terminal With relay 2 once picked up it will be stuck up through a stick circuit including its stick contact 84 and front contact of relay SR Stepping relays b and 2 are now energized, so-that the second station selecting code character may be transmitted.

This second station selecting code character is applied to the control selecting relays CSA and CSB through the following circuits: (1) beginning at the terminal jumper 50 (see Fig. 2A), front contact I32 of the code determining relay CD wire I33, front contact 29 of the stepping relay b, back contact 30 of the stepping relay c, wire 56, back contact 3I of the relay OBS,

winding of the control selecting relay CSA to the common return wire C, and (2) the circuit for the control selecting relay CSB is open; because this circuit includes the contact I35 of the code determining relay CD and since this wire has no code determining jumper in it,-the line B will be deenergized during this second station selecting period, during which the line A is energized by current of positive polarity, as indicated in the control cycle column of Fig. 3 of the drawings, this because the relay IM has been dropped in the meantime by lifting of contact II2 of the relay 17.

Let us now observe what effect the positively energized condition of line A and the deenergized condition of line B has on the apparatus of the way station, shown in Figs. 20 and 2D. With the line relay LA energized to the right, the polarity code signifying relay A will be energized tothe right through the following circuit: beginning at the terminal polar contact 56 of the relay LA to the right, front contact 32 of the relay SR wire 61, back contact 58 of the stepping relay 3, front contact 59 of the stepping relay I,

this stepping relay being stuck up until the end of the cycle, winding of the relay A to the common return wire C. The polarity code signifying relay B is not operated at this time because the line relay LB assumes its neutral d-eenergized condition. The continuity code signifying relay M is not changed during this second station selecting period because this energizing circuit is broken at the front contact I6 of the relay LBP but the continuity code signifying relay N is operated to the left through the following circuit: beginning at the terminal front contact I 36 of the relay LAP back contact of the relay LBP wire 8I, back contact 82 of stepping relay 5, front contact 83 of stepping relay I, through the winding of N to the common return wire C. With the relay A now energized to the right and the relay N now energized to the left, the code relay SO2 is energized during the next or third stepping period through the following circuit: beginning at the terminal contact 85 of the relay N to the left, contact I38 of the relay A to the right,

jumper I39, front contact I45 of the code relay SGI, lower winding of the code relay SO2, front contact I iI of the stepping relay 2, back contact I42of the stepping relay 3, back contact 93 of the half-step relay H8 wire 94, and back contacts I5 and 15 of relays LBP and LAP respectively, to Relay SO2 is then stuck up through a stick circuit including its stick contact 55, wire I25, and front contact 35 of relay SR Attention is directed to the fact that the circuit just traced includes back contact 93 of the relay H3 This relay HS2was actuated to its retracted position during the transmission of the second station selecting code immediately following the picking up of the stepping relay'Z by reason of the closure of the following circuit: beginning at the terminal of the field station battery, front contact I5I of relay BS front contact II? of the stepping relay 2, back contacts I58, H9, I29 and IZI of the stepping relays 5, I and 8, respectively, upper winding of the half-step relay HS and through front contact I22 of the line repeater relay LAP to the common return Wire C connected to the midpoint of said field station battery. The closure of the circuit for the upper winding of relay HS just traced applies a current neutralizing the effect of the current in the lower winding in this relay HS so that the relay I-IS assumes its deenergized position, opening its two stick contacts I55 and I5I, so that this relay HS now remains deenergized until it is again picked up by current flowing from right to left through its upper winding, which occurs with the stepping relay 3 en ergized and one, the other or both of the relays LAP and LBl energized. In this connection it should be remembered that the stepping relays I and 2 both remain stuck up, as is also trufe of the remaining stepping relays until the end of the code cycle.

The above description points out the manner of selection of channel circuits for energization in response to the station selection coded impulses. These channel circuits which are connected to code signifying relays A B M and I to the other terminal N are closed by the picking upof relay I and. opened by the picking up of relay 3. Since relay t is picked up before the operation of any stepping relay which operates in response to the indication portion of a tandem cycle (later explained), it will be apparent that any energy applied to conductors 6?, II, II and 8| by the operation of relays LA L13 LAP and LBl by the conditioning of the line circuits during the transmission of indications in a tandem cycle, will be inefiective to change the positions taken by these code signifying relays during the control portion of a tandem cycle.

Referring again to the table in Fig. 3, it should be remembered that the second station selecting character of plus on the line A and with the line B open has been. transmitted, and that the next operation is a stepping period during which both the line A and the line B are deenergized. This is accomplished, referring to Fig. 213, by dropping of the half-step relay HS in the central office, and its shifting of the contact I55 from'itsattracted to its retracted position. This relay H8 is retracted by closure of the following bucking circuit: beginning at the terminal of the central oflice battery, front contact I52 of the relay HS, front contact 98 of the stepping relay b, back contacts 99, I66, IEII and I52 of stepping relays c, J, g and h, respectively, upper winding of the relay HS wire BIL'through the front contact 95 of the relay LAP to battery connection C. This relay HS" now drops by reason of the bucking action of its two energized windings, and upon dropping opens its two stick contacts I55 and I52, for reasons already explained in connection with the relay HS Shifting of the contact I85 of relay 1-18 from its attracted to its retracted position completes the following energizing circuit for the lower winding of the impulsing relay IM: beginning at the terminal back contacts III I, I08, I59, I55 and III of relays h, g, 1, SE and 0, respectively, front contact I I2 of the relay 1), lower winding of the relay IM, back contact I55 of the relay HS Wire I31, and front contact 36 of the slowrepeater relay SRP, to

Picking up of the impulsing relay 1M opens both the line A and the line B, thereby causing a stepping operation to take place during which the stepping relays c and 3 are picked up through the following circuits: (1) front contact 44 of the relaySR. (see Fig. 2A), contacts I3 and I4 (retracted) wire I8, contact I'I (retracted) contacts 4i and 52 (retracted) front contact 43 of relay b, winding of the relay 0, and (2) front contact 35 of relay SR (see Fig. 2C), contacts I I6 (retracted) wire I25,c ontacts 45, 46 and M (all retracted), front contact 48 of the stepping relay 2, through the winding of the stepping relay 3 The completion of these two circuits causes the stepping relays c and 3 to be picked up and stuck up through their stick contacts I53 and I54, respectively. Picking up of the stepping relay 0 closes the fol lowing energizing circuit for the control selecting relay CSA:-beginning at the terminal contact of lever L (see Fig. 2A), front contact I48 of the code determining relay CD wire I55, front contact 30 of the stepping relay 0, wire 55, back contact SI of relay OBS, winding of the control selecting relay CSA to the common return wire C. Relay IM now drops for obvious reasons allowing the contacts I IGand I41 of reacter.

Since the wire leading from front contact 62 of the stepping relay c is not connected to any source of current, the line B will be deenergized during this control code selecting period, so that the line A will be energized by current of negative polarity and the line B will be deenergized, as signified by the code table in Fig. 3 of the drawings. With the relay LA now energized toward the left the polarity code signifying switch machine control relay SMR will be energized through the following circuit: beginning at the terminal contact 66 of the relay LA to the left (see Fig. 20), front contact 32 of the relay SR wire 61, front contact 68 of the stepping relay 3, front contact I56 of the code relay SOZ, through the winding of the switch machine control relay SMR, to the common return wire C connected to, the mid-point of the way station battery. The closure of the circuit just traced operates the relay SMR to the left and completes the reverse circuit for the switch machine SM, thereby operating this switch machine to its take-siding position.

Referring now to Figs. 2A and 2B, attention is directed to the fact that relay IM is picked up to terminate the control code which deenergizes relays LA and LAP. This effects the energization of the ofiice battery selecting relay OBS through the following circuit: beginning at the terminal of the central office battery, front contact 44 of the relay SR. (see Fig. 2A), back contact I3 of relay LAP back contact Id of relay LBP, wire I 8, front contact I! of relay HS back contacts I43 and I44 of stepping relays g and SE", front contact I45 of stepping relay 0, wire I51, winding of the relay OBS, wire I58, front contact I59 of the impulsing relay IM to the other terminal With this relay OBS once picked up, it is stuck up through a stick circuit including its stick contact I31. The stepping relay 1 is picked up in multiple with relay OBS which results in dropping of the relay IM due to contact I09 of relay Relay 6 at the station is picked up over an obvious circuit through back contacts I5 and I5. However, with relay OBS energized and relay FBS 'deenergized, the lines A and B cannot be energized from either end. Picking up of the oflice battery selecting relay OBS will of course cut off the control formerly effected by the relays CSA and CSB, so that the lines A and B can no longer be energized from the central office, and since the relay OT (see Fig. 2D) was not energized during the initiating period of the cycle under consideration, as is obvious from the pick-up circuit for this relay OT, the station battery selecting relay FBS (see Fig. 2D) will not be picked up, sothat the lines A and B cannot be energized from eitherend of the system. Under this condition it is obvious that after an interval of time the slow acting relays SR and SE. (see Figs. 2A and 20) will assume their retracted positions, and a short period of time thereafter the slow repeater relay SRP (see Fig. 2A) will also assume its deenergized retracted position.

Dropping of the slow acting relays SR. and SR will of course effect deenergization of relay OBS, the stepping relays a, b, c, f, and I, 2,

3,6, which were formerly stuck up through front contact 40 of relay SR, and front contact 35 of relay SR respectively. With the stepping relay a. now assuming its .retracted position, and also with the ofilce battery selecting relay OBS deenergized, the control selecting relay CSB is returned to its normal right-hand position through its normal'circuit, heretofore traced, and briefly comprising back contacts 60, 6|, and 62 of relays a, b and 0, Wire 63, and back contact 64 of relay OBS, so that the system is now returned to its original and normal condition, in which the line B is energized by current of positive polarity and the line A is deenergized. It is of course understood that the picking up of the stepping relay c (contact 2I) closed a pick-up circuit for the lever relay LCR and broke the stick circuit for the relay CD so that these relays LCR and CD have been returned to their normal condition. Contact I49 of relay CD is employed so that relay LCR can only be picked up when relay CD is up.

In the same manner as just explained, with both lines A and B deenergized for a sufficient period of time to deenergize relay SRP, the deenergization of relay SR will be effected, so that the relays I, 2, 3, 6, SOI, and SO2 are returned to their normal deenergized conditions. Also, it should be understood that the simultaneous energized condition of relays SOI and SO-2 signifies a particular station selecting code and results in the circuit through the contact I55 of relay SOZ being complete at that point,

so that a specific code charactermay be transmitted to that particular field station through said contact.

Briefly summarizing in general terms this operation of the transmission of controls alone, above described in detail, the manipulation of the levers or the like by the operator in the control office results in the energization of a particular code determining relay such as CD which in turn energizes the relay 0ST for a control oflice start. This brings about the energization of the normally de-energized line A with polarity,

which fails to pick up the selecting relays SE in the control oilice and at the several field stations, with the result that the stepping operation starts with the group of relays for transmission of controls. The slow-releasing relays are energized in the control office and at each field station to indicate the beginning of an operating cycle, these relays being maintained energized throughout the operating cycle, on account of their slow-releasing characteristics, notwithstanding the momentary de-energization of the line circuits during the stepping operation.

After this conditioning or initiating period, both lines A and B are simultaneously opened by the impulsing relay IM to pick up the first stepping relay a in the control oifice and the corresponding first relay I at the field stations. With the first stepping relay in in the control oifice energized,'the three position polar relays CSA and CSB (Fig. 2A) controlling the polarity of energization of the lines A and B respectively, or their de-energized condition are connected, through code buses 54 and 59 and through contacts on the particular code determining relay CD then energized, to code jumpers 5| and 52 by means of which these relays CSA and CSB may be respectively energized with either polarity or de-energized, depending upon the cod-e call for the particular station to which the controls are to be transmitted. For example, in

the specific case assumed, the code jumpers 5| impulsecombination of is, of course,

only one of the 8 different combinations which may be applied to the lines A and B after the first step.

The energization of the first stepping relay a in the control ofiice results in the de-energization of the impulse relay IM, which closes the lines A and B, so that these lines will be'energized in accordance with the code call. This energization of the lines A and B is in turn followed by another operation of the impulse relay IM, thereby causing a second stepping relay of the control group -in the control office and each field station to pick up. This shifts the connections to the relay CSA and CSB to another pair of code buses which similarly may be respectively energized with either polarity or de-energized to provide any one of 8 difierent code combinations. As a result of In this connection it should be understood for station-selection maybe used at one location, and operated by the same apparatus, the particular code call to which each of these relays as SO-2 responds being determined by the position of the code jumpers as 89 and I39.

Following the selection of the station being .called, on the next or third step, a code combination for the desired control may be transmitted. Any one of 8 different control conditions may be transmitted on this third step, which may be used to control switches or signals in any desired way and if necessary, any one of 8 other difierent control conditions may be transmitted on another .step, and so on. To avoid complications in the illustration and description, no attempt has been made to show how these control codes may be utilized to govern traific, the operation of a switch machine asshown and described, being sufficient tomake clear how the system may be applied as desired, to varying operating conditions.

However, the present disclosure sets forth more particularly how any two of four different control conditions may be transmitted on this third step, which control conditions may be used to control switches, signals or the like. More specifically, thepolarity of the A line may be determined in accordance with one control lever to control a two-position relay such as relay SMR, as

above described; and similarly, the polarity of the B line may be determined in accordance with the position of another lever to thereby control another two-position relay, similar to relay SMR.

-In other words, two two-position magnetic stick type control relays, such as relay SMR, may be controlled on each step in accordance with their respective levers after the station is selected. Although only the control for relay SMR. has been shown,it is believed sufiicient to point out that a relay similar to relay SMR for the third step may be connected to the front point of contact 12 of stepping relay 3 through a front contact of the relay SO-2 similar to the relay SMR, and also that similar control is provided for each pair of control relays for the succeeding steps when a greater number of control steps is employed. To avoid complication in the illustration and description, no attempt has been made to show how these control relays may be utilized to govern traific, the

clear how the system may be applied to varythe trafiic operating conditions.

the wire I84 and stick contact I6 I After the energization of the lines A and B,

following the third step, and when the lines A and ;B are both broken by the impulsing relay IM, the

relay OBS in the control office is energized, connecting the lines A and B together and to the common wire. In the case of a cycle for the transmission of controls alone as assumed, the line circuits A and B are. thus deenergized, notwithstanding the dropping of the impulse relay IM,whereupon the slow-releasing SR relays drop, and the system is restored to the normal condition of rest, ready for another operation.

' Indication cycle (in-coming) .-Let us now observehow the entrance of a train upon the detector track circuit containing the track relay TR (see Fig. 2D) is able to initiate an indication cycle and will result in the illumination of the indicating lamp I in the central office (see Fig.

Referring to Fig. 2D, dropping of the contact Itfl of the track relay TR will result in momentary opening of the stick circuit for the lower winding of the change relay CH including The momentary breaking of this stick circuit will effect deenergization of the relayCH, this because the front contact I62 of the indication station selecting pulsing determining relay LIR is open at this time. Dropping of the change relay CH closes the following circuit for thecontinuity indicating pulsing relay CBP beginning at the back contact of the relay SR (see Fig. 2C), back contact I65 of the relay LAP back contact I66 of the change relay CI-I, back contact 34'of the relay SR through the lower winding of the relay CBP to the other terminal of the battery. With the relay CBP picked up, it will be stuck up through its stick circuit including the back contact I'IZ of the stepping relay 6, back contact I13 of the stepping relay I, wire I15, winding of relay CBP and the stick contact I'M of this same relay. Closure of this .circuit and the picking up of the relay CBP eiiects the opening of the line B at vback contact Ill and de-energization of the line repeater relay LBP in the central office (see Fig. 2A), thereby closing its back contact I61,

resulting in closure of the following circuit for the field starting relay FST: beginning atthe terminal back contact I61 of the relay LBP, back contact I68 ofthe relay SRP, back contact 24 of the ofiice starting relay 0ST, winding of the field starting relay FST, to the other terminal The relay FST, if once picked up, will be stuck up through its front contact I69 and the front contact 4|] of the relay SR" as soon as this slow acting relay SR picks up, which will happen a little later.. Picking up of the field starting relay FST will prevent the picking up of the relay 0ST thereafter, and will close the following energizing circuit for the control code selecting relay CSA: beginning at the terminal (-1-) of the central ofiice battery, back contact I10 of the relay SRP, front contact ill of therelay FST, back contact 2'? of the relay 0ST, wire 4, back contacts 28, 29

and 30 of the stepping relays a, b, and c, wire 56,

back contact 3| of the relay OBS to the control code selecting relay CSA, the other side of which is connected to common return wire C.

With the line A now energized by current of positive polarity (as indicated in the initiating period of the indication cycle, see Fig. 3), the front contact I16 of the line repeater relay LA]? (see Fig. 2C) is closed, thereby reclosing the line B through the medium of the upper winding of the station selecting and pulsing detercontact 35 of the slow acting relay SR mining relay LIR the contact I11 of the continuity code impulsing relay CBP now being in its raised position. The completion of the circuit picks up the relay LIR and with it once picked up it will be stuck up through its stick circuit including its front contact I18 and the front Also, this picking up of relay LIE. results in reenergization of the relay CH, this through front contact I62 of relay LIR It is thus seen that the initiating period of the-indication cycle constitutes plus polarity for the A line and zero followed by plus polarity for the line B, as indicated at the initiating point in the indication cycle column of Fig. 3 of the drawings.

It should be noted that the relay LIR cannot be picked up unless the relay CBP has its front contact I11 closed, and further that the relay CBP cannot be picked up unless the relay SR. has its contact 34 down unless the relay LIB. is already up and has its front contact 202 closed. For this reason the relay L115. can only be picked up during the initiating period of a cycle, and since during an initiating period the relay CBP can only pick up if the change relay CH is down the relay LIR picks up only during a cycle in which indications can be transmitted, namely a tandem cycle or an indication cycle.

It is desired to point out herethat duringthe initiating period of the indication cycle, which consisted of plus energization of the line A and deenergization followed by plus energization of the line B the relays SE (see Fig. 2B) and SE? (see Fig. 2D) were picked up through the following pick-up circuits: (1) starting with the terminal at the central oince, contact I80 of the line relay LA", back contact I8I of slow acting relay SR wire I82, upper winding of the relay SE to the other terminal and (2) contact 66 of the relay LA to the right (see Fig. 20), back contact 32 of the relay SR wire I88, upper winding of the relay SE to the other terminal These indication-only selector relays SE and SE if once picked up, will stick up through their stick circuits including their stick contacts I83 and I84 respectively, which in turn are connected through front contacts 40 and 35 of relays SR and SR respectively, to the plus side of the battery. It may be pointed out that these relays SE and SE, are only energized if an indication alone is to be transmitted, that is are not energized for a control cycle and are not energized for a tandem cycle, and these relays result in causing the stepping relays f and 6 to be picked up first, that is, the relays a, b and c and stepping relays I, 2 and 3 remain deenergized during an indication cycle.

Also, it should be remembered that during the initiating period the line B was for a time deenergized and was then energized by current of positive polarity. The momentary condition of line A energized and line B deenergized completed the following pick-up circuit for the relay OT located only at the last station namely in the End Battery Control Station:-beginning at the terminal back contact 35 of the relay SR front contact I65 of the relay LAP back contact I15 of the relay LBP wire I19, winding of the relay OT, to the other terminal minus.

Picking up of the relay SE (see Fig. 2B) effected closure of the following energizing circuit. for the upper winding of the relay HS during the initiating impulse of the indicating y 1e;-beginning at the terminal front contact I81 of the relay- SE, back-contacts I00, IN and I02 of relays ,f, g. and h, upper winding of the relay -HS, wire 94, and front contact 95 of the relay LAP". With the relay HS once picked up'it will of course be stuck up for reasons heretofore given. In the same manner as just explained in connectionwith relay SE, the relay SE (see Fig. 2D) through the picking. up of its contact I90, closes an energizing circuit for the relay HS which circuit may be traced as;

follows: beginning at the terminal contact I90 of the relay SE back contacts II9, I20 and I2 I, respectively, of relays 6, 1 and 8, upper winding of the half-step relay HS wire I24, and through front contact I22- of the line repeater relay LAP to the common return wire C connected to the mid-point of the way station battery.

After a short period of delay following the energization of the slow acting relay SR (see Fig. 2A) in the central oflice, a slow repeater relay SRP is energized, thereby closing its contact 36 and effecting energization of the impulsing relay IM (see Fig. 23) through the upper winding, which results in opening its contacts 38 and 39 to constitute a stepping code.

With relays 118 and H8 now energized and with the relays SE and SE now energized the stepping relays f and 6 are energized through the following respective circuits: (1) beginning at the terminal front contact 44 of the relay SR (see Fig. 2A), back contacts I3 and I4 of line repeater relays LAP and, LBP, wire I8, front contact I1 of relay HS", back contact I43 of relay 9, front contact I 44 of relay SE and winding of relay 1 to and (2) beginning at the terminal of the way station battery, front contact 35 of therelay SR (see Fig. 2C) back contacts I5 and I6 of the line repeater relay LAP and LBP wire I26, front contact 45 of the relay HS back contact I21 of the stepping relay I, and front contact. I28 of the stepping relay SE through the winding of the stepping relay 6, to the other terminal of the way station battery.

With the relay SE now energized as heretofore explained, the oflice batteryselecting relay OBS is energized as soon as the relay IM (see Fig. 2B) is up through the following circuit:- beginning at the terminal plus, now connected to the left handterminal of relay 1 as above traced, wire I51, winding of the relay OBS, wire I58 and front contact I59 of the relay IM, It should be noted that the picking up of relay SE results in the immediate picking up of relay HS through contact I81 of relay SE and that relay IM is picked up as soon as relays SE, HS" and SRP are up, namely through contacts I06, I05 and 36, respectively, of these relays. It has just been pointed out that the stepping relay 6 was picked up during the first stepping period and it should be noted that there is a branch circuit to energize the field battery selecting relay FBS. This branch circuit leads from the left terminal of relay 6 and passes through front contact 260 of the relay OT, so that the relay FBS is picked up with the relay 5 and is then stuck up through its stick contact 252 and contact 35 of relay SR The first stepping relays of the indication portion of the'system, namely the stepping relays and 6 are now energized, and stuck up through their respective stick contacts 98 and 216, and the system is placed in condition for transmitting the first station registration impulse 2n), contact 2l6 of the relay A tn the left, jumpfrom this particular way station to the central oflice, it being understood that the ofiice battery selecting relay OBS was picked up in response to the picking up of the relay SE as already explained.

With the stepping relay 6 now energized (see Fig. 2D) the station registration code defining jumpers I95, I96 and I91 will be able to impress the particular code signified by these jumpers resulting in the reenergization of the continuity indicating pulsing relay CBP this relay CBP which was picked up and stuck up during the initiating period, having been deenergized upon picking up of the stepping relay 6 as the result of the opening of back contact I12 of this relay 6. This new energizing circuit for the relay CBP may be traced as fol1ows:starting at the terminal of the way station battery, station registration code defining jumper I90, front contact I98 of the stepping relay 6, back contact I99 of the stepping relay 1, back contact 200 of the stepping relay 8, wire I, front contact 202 of the relay LIRP, front contact 34 of the slow acting relay SR through the lower winding of the relay CBP to the other terminal Picking up of the relay CBP with the field battery selecting relay FBS now energized (as heretofore explained) lifting of the contact I11 of this relay CBP will effect opening of the line B, the source of energy now being at the field end of the system, the office battery being disconnected because the office battery selecting relay OBS is energized, and since the relays CAP PAP and PBP .(see Fig. 2C) are deenergized, current of negative polarity will fiow in the line A, this because the line A at the field end thereof is connected to the positive terminal of the battery, thus resulting in a negative code for the line A and a zero code for the lineB during the first station registration period of the indication cycle, as shown in Fig. 3 of the drawings.

Referring now to Figs. 2A and 2B of the drawings, let us observe what effect negative energization of the line relay LA and deenergization of the line relay LB will have on the polarity code signifying relays A and B and on the continuity code signifying relays M and N 1 With the relay LA energized toward the left, the following circuit will be closed for the relay A (see Figs. 2A and 2B) beginning at the terminal of the central office battery, contact I80 of the relay LA toward the left, front contact I8I of the relay SR wire 205, back contact 206 of the stepping relay h, front contact 201 of the relay f, winding of the relay A, thus resulting in operation of the relay A toward the left. Since the line A is energized and the line B is deenergized, current of negative polarity will be applied to the continuity code signifying relay N through the following circuit:beginning at the terminal of the central ofilce battery, front contact 208 of the relay LAP back contact 209 of the relay LBP wire 2 I 0, back contact 2| I of the stepping relay h, front contact 2I2 of the stepping relay 1, through the winding of the continuity code signifying relay N, to the common return er 2", lower Winding of the code relay KOI, front contact 2I8 of the stepping relay 3, back contact 2I9 of the stepping relay g, back contact I03 of the half-step relay I-IS, wire 239, back contact 220 of the relay LBP", back contact 22I of the relay LAP", to the terminal With the code relay KOI energized, it is stuck up through its stick contact 222 and the front contact 40 of the relay SR in series.

The double zero code for causing the stepping relays to take their second step'to effect picking up of the stepping relays g and 1 is obtained by the picking up of stepping relay 1 in the central office applying current of negative polarity to the upper winding of the half-step relay HS, thereby causingthe currents in the two windings of the relay HS to neutralize each other and causing this relay HS to assume its deenergized position shifting its contact I05 from the raised to the lower position, and thereby resulting in the energization of the lower winding of the impulsing relay IM through a circuit readily traced and including the front contact I09 of the stepping relay J. Energization of the impulsing relay IM will of course break the circuits of both lines A and B and thereby cause the second stepping relays at the central ofiice and at the particular,

1, to be picked up all in a manner similar to that already described hereinbefore in connection with other stepping relays. These relays g and '1 are then stuck up through their stick contacts 223 and 228 respectively. i

With the stepping relay 1 (see Fig. 2D) picked up, a particular code as determined by the code jumpers I95 and I91 causes the relays CAP and PB]? to be picked up through the following respective circuits: (1) beginning at jumper I95, contacts 210, 21I, wire 203, contact 212, through the winding of relay CAP to and (2) beginning at jumper I91, contacts 213 and 242, wire 246, contact 214, through the winding of relay PBP to the terminal of the battery, (see Fig. 2C). The picking up of relay CAP effects the openingof line A and the picking up of the relay PBP causes current of positive polarity to be applied to the field end of the line B, resulting in current of negative polarity flowing in the line B, so that the next code is in effect a zero-minus code as indicated for a .second station registration code, as indicated in Fig. 3 of the drawings.

code will have on'the apparatus in the central office. With the line A deenergized, the position of the code relay A will not be changed; but with the line B energized negatively, the line relay LB assumes its left-hand position. Therefore, current of negative polarity is applied to the code relay B through the following circuit:beginning at the terminal ,contact 224 of the relay LB to the left, (see Fig. 2A) wire 225, back contact 226 of the stepping relay h, front contact 221 of the stepping relay 1, winding of the relay B to the common return wire C, thus operating relay B to the left. Also, under this condition of the lines A and B, the relay LAP will be deenergized and the relay LBP will be energized, so that the relay N is energized to the right through the following circuit:beginning at the terminal front contact 209 of the relay LBP (see stepping relay), namely stepping relays g and Fig. 2A), wire 2l0, back contact 2| I of the relay h, front contact 2|2 of the relay 1, winding of the relay N to the common return wire C, thus energizing the relay N to the right.

The relay M will be energized to the left through the following circuit: beginning at the terminal back contact 22! of the relay LAP (see Fig. 2A) front contact 226 of the relay LBP, wire 22! back contact 230 of the relay h, front contact 23! of the relay f, winding of the relay M, to C thus operating the relay M to the left. During the next stepping period, namely when the relays LAP and LBP both have assumed their deenergized positions, the following pick-up circuit for the code relay KO2 will be closed:beginning at the terminal contact 2E5 of the relay N to the right (see Fig. 2B), contact 233 of the relay M to the left, contact 234 of the relay B to the left, through jumper 235, front contact 236 of the relay KOl, winding of the relay KO2, front contact 23? of the stepping relay g, back contact 238 of the stepping relay h, front contact I03 of the half-step relay HS wire 239, back contact 220 of the relay LBP back contact 22! of the relay LAP", to the other terminal of the central ofice battery. With this relay KO2 picked up it will be stuck up through a stick circuit including the stick contact 232 and the front contact 45 of the relay SR in series.

The third zero-zero code, namely both lines deenergized, will be effected by the impulsing relay IM in a manner as already explained, and will result in picking up of the stepping relays h and 8, and the indication code will then be transmitted in a manner presently described. With relays h and 8 once picked up they will be stuck up through their respective stick contacts 240 and 242 until the end of the indication cycle. Although four distinctive conditions can be transmitted at the same time during this third step of the, indication cycle, as is obvious from the fact that four front contacts 211, 230, 206 and 225 are available for this purpose, only one of these conditions has been specifically shown in the drawings, namely the condition of occupancy of the detector track circuit containing track relay TR. (see Fig. 2D) as manifested by the current flowing in front contact 226 of relay h. It will be noted that with the stepping relay 8 energized, the polarity indication pulsing relay PBP will be energized through the following circuit, whereas the relay CAP CBP and PAP will remain deenergized:beginning at the terminal of the way station battery, back contact 24! of the track relay TR, front contact 242 of the stepping relay 8, wire 2&6, front contact 21 3 of the relay LIR winding of the relay PBP With the relay PB]? energized and relays CAP and CBP and PAP all deenergized, the terminal of the end battery will be connected to both the line A and theline B through front contacts 248 of the relay FBS, and through front contact 250 of relay PBP back contact 25! of relay PAP back contact 252 of relay CAP and back contact ll! of relay CBP thus resulting in negative current flowing in the lines A and B and resulting in a minus-minus code for an indication code in the indication cycle (see Fig. 3).

Let us now observe what effect this minusminus code will have on the central office apparatus. Relays LA and LB are actuated toward .the left and relays LAP and LBP are picked up as a result of the minus-minus .code. With the relay LB actuated to the left the following circuit for the indication relay IR is a control cycle.

closed:-beginningat the terminal of the central office battery, contact 224 of the relay LE to the left, wire 225, front contact 226 of the stepping relay h, front contact 243 of the relay KO2, wire 244, winding of the relay IR, to C.

The completion of this circuit results in the operation of the polar-magnetic stick relay IR to the left thereby illuminating the indicating lamp I through the contact 245.

The picking up of the last stepping relay h in the central office will result in the deenergization of the half-step relay HS and dropping of this relay HS and the shifting of the contact I05 of relay HS results in energization of the impulsing relay IM, which upon lifting of its con-.-

tacts 38 and 39 opens the lines A and B to effect further stepping of the system. Since, however,

there are no more stepping relays to function, the impulsing relay IM will not be deenergized as it was heretofore through the medium of the next.-

stepping relay picking up, and therefore this impulsing relay IM will remain energized, maintaining the break in the lines A and B, which after a short interval of time results in deenergization of the slow acting relays SR and SRP in the central oflice, and dropping of the slow acting relay SR at the particular way station under consideration, which in turn results in dropping of the various relays OBS, SE", FST, J, g and h,

way station under consideration, so that upon deenergization of these various relays the lines A and B are returned to their normal condition,

under which condition line A is deenergized and 1 line B is energized by current of positive polarity.

Referring back to the control cycle operation, attention is directed to the fact that although only one distinctive control impulse was transmitted during the control cycle described, this control impulse passing through the front contact 68 of the stepping relay 3 and resulting in the operation of the switch machine relay SMR, that four distinctive control impulses can be transmitted on the same step, namely the third step of Similarly even though only a single indication has been described as being transmitted in the indication cycle, this indication impulse passing through the front contact 226 of the stepping relay it (see Fig. 2B) and resulting in the operation of the indicating relay IE, it is to be understood that four distinctive indications can be transmitted on this same step, namely, the third step of the indication cycle. Also, even though only one way station has been illustrated in Figs. 2C and 2D of the drawings, it is of course understood that the system as disclosed is capable of communicating with sixtyfour different way stations, this being apparent from the fact that eight relays corresponding to the code relay SO-l may be employed, and for each of these relays SO| eight code relays SO2 may be used, so that the entire system may have sixty-four relays corresponding to the code relay SO2.

It should also be noted that the station selectin the centralv onice, and resulting in droppingv of 0 the relays LIRF, SE OT, FBS, 6, 1 and 8 in the I ing and pulsing determining relay LlIR, can pick cuit for its associated relay LIR this because the line B beyond the first station that has its relay CBP up will be open, so that the remaining LIR relays will not be picked up. It is of course readily apparent that the indication-only selecting relays, such as the relays SE and SE are used for the purpose of starting the cycle at the fourth stepping relay in the particular arrangement of the relays illustrated and that these relays SE and Slit are only up during an indication cycle and are not up during a tandem cycle during which indications are transmitted in addition to the transmission of control impulses.

Attention is directed to the fact that the circuits for the relays M, N M and N v are open at the line repeater relays LAP LBP LAP or LBF during each zero-zero code, this in order to prevent the circuit for these relays operating such relays during such stepping impulse and during which the code relays, such as SOI and KOI are operated in accordance with the po-' sitions of the relays A", B M", N", A B M and N Tandem cycZe.Let us now assume that the ready explained in connection with the control cycle (see Fig. 3), and that the line B is opened at the contact I'll (see Fig. 2C) because the relay CBP has been picked up in response to dropping of the change relay CH, by reason of the fact that an indication is to be transmitted from the way station, shown in Fig. 20, to the central oifice, this because .the relay TR has been picked up and has momentarily broken the stick circuit of this relay CH at contact I60. Under this condition the relay LIR will be picked up through the front contact ll! of relay CBP and the front contact I76 of the relay LAP so that the station nearest the control office is rendered effective to transmit indications. Since the line A is energized negatively during the conditioning period, the SE relays in the control oifice and at the field stations are not energized, and the stepping starts with the group of relays for the transmission of controls, the sameas if the cycle was to be a control cycle alone. The opening of the line B, prior to the initiation of the cycle,

however, results in the energization of the relay.

OT at the end of the line, which is the case with an indication cycle alone. I

In the same manner as already explained, the

slow acting relays SR and SRP (see Fig. 2A of the drawings) and the slow acting relay SR. (see Fig. 2C of the drawings) are picked up, as a result of which the relay LIR (see Fig. 2C) will be stuck up, and the impulsing relay IM (see Fig 2B) will be energized, thereby opening its contacts 38 and 39 opening both the line A and the line B, and resulting in a zero-zero 'code' comprising the first stepping character as indicated in the table headed tandem cycle in Fig. 3 of the drawings. This breaking of the lines A and B will cause the stepping relays a and I to be picked up in a manner as already explained. Since the station to be selected is the same as the station selected during the description of the control cycle, the next four steps of the tandem cycle-will be exactly the same as that of'the control cycle, as clearly indicated in the column tandem cycle shown in Fig. 3 of the drawings. The control code character itself, however, will be slightly different, in that under this condition the line A will be energized by'current of positive polarity, whereas for the transmission of thecontrol code as indicated in the control cycle fact that the lever L has been returned toits normal plus polarity position.

At the end of the control cycle, as-previously explained, the relay OBS in the control office picks up and connects the lines A and B together to the common wire, and the impulsing relay I M drops to close the lines A and B in the control ofiice. This de-energization of the lines A and B picks up the relay FBS (see Fig. 2D) in multiple with the stepping relay 6, the relay OT being energized in the case assumed; and when the relay FBS is thus picked up, the battery II at the field station is coupled to the lines A'and B, so that the system continues stepping for th transmission of indications.

Thus, the so-called tandem cycle in effect consists of an indication cycle immediately following a control cycle, Without an intervening period of blank with the system in the normal condition.

ing back the transmission of indications while controls are being transmitted from the control- In the system of the type described, in

cannot be transmitted simultaneously; and in-.v stead of transmitting controls alone on repeated cycles so long as there are any new controls-to The purpose of this arrangement is to avoid holdbe transmitted, holding back transmission of indications, during such time, in accordance with this invention, the so-called tandem cycle is provided with the result that controls and indications are transmitted alternately so longas both are ready, neither the indications being unduly delayed' for the controls or Vice versa. By reason of. this organization, the operator may use the line freely, knowing that in so doing no indicae tions are being suppressed.

Obviously, since the indication to be transmitted from the way station to the central o-flice during this tandem cycle originated at the same way station as did the indication transmitted during the indication cycle, the station registra tion code transmitted during the fifth and sixth step, namely, when relays ,f and g and 6 and l are picked up will be exactly the same as the codes transmitted during the indication cycle, so that the next four code steps of the tandem cycle will be the same and will be carried out in exactly the same manner as already described in connection with the indication cycle. The last code step or indication code, will, however, be different in that picking. up of the track relay TR will leave the circuit heretofore traced and including the contact 24! of this track relay TR. open, so that the relay PBP will not be energized during the indication code period,.and-theline A will be connected to the positive terminal of the end battery and the line B will be connected to drawings and unnecessary elaboration in the description the present invention has been illustrated to show only a single way station in Figs. 2C and 2D, although two way stations have been illustrated in Fig. 1 of the drawings, and in this connection it is to be understood that the invention may be extended to employ 64 way stations without additional apparatus than what has been illustrated except that a station selecting relay, such as the relay 80-2, and a station regise tration relay such as the relay KO-2 are necessary for each way station, and additional relays corresponding to the station selecting relay SO! and the station registration relay KOI are necessary for each eighth way station. Also, in

this connection attention is directed to the fact that only one of the station selecting and pulsing determining relays LIR even though sixtyfour relays of this kind may be used, can be energized at one time, so that in-coming codes can be pulsed or initiated at only one way station atone time, and obviously this coding or impulsing of the lines cannot interfere with the coding or inipulsing at the central office by reason of the interlock between the field starting relay FST and the ofiice starting relay 0ST shown in Fig. 2A of the drawings, also, since the office battery selecting relay OBS and the field battery selecting relay FBS are either both energized or both deenergized 3. is another reason for avoiding an in-coming and an out-going code being transmitted at the same time.

The relay OT known as an indication conditioning relay is a relay that determines that the field battery selecting relay FBS shall be picked up as soon as the stepping relay 1 and its corresponding stepping relay 6 is picked up. In other words, the relay OT determines that an indication is to be transmitted from a way station to the central ofiice and this relay OT through the medium of its front contact 260 will pick up the field battery selecting relay FBS simultaneously with the picking up of the stepping relay 6, this through the medium of the wire 26I included in the pick-up circuit for the field battery selecting relay FBS. The battery selecting relay FBS will of course be stuck up through its stick contact 262 as soon as it has once been energized, and in a similar manner the relay 0T will be stuck up through its stick contact'263 when it has once been picked up, the stick circuits for these relays OT and FBS include the contact 35 of the slow acting relay SR so that both of the relays OT and FBS will again be deenergized during the period of blank, known as the normal period in the three different cycles illustrated in Fig. 3 of the drawings. It may be pointed out here that the resistance units 265 and 265 shown in Fig. l of the drawings (the unit 265 also being shown in Fig. 20 of the drawings), are of such ohmic value that the current flow through the pick-up winding of the relay LIR. will be the same for each of these relays irrespective of the distance the way' station under consideration is located from the central office. In other words, these resistance units 2%5 and 255 may be said to be current balancing resistance units.

From the foregoing description, the general operating characteristics of each of the relays employed in the system under consideration should be understood, but in order to more clearly understand the conventions employed, these conventions will be further discussed. It will be noted that the, relays A B M N 'and IR, located in the central oiiice, and the relays A ,'B M N and SMR located in the first way station'of the system, each have a small black square near the lower righthand corner thereof. This conventional illustration represents these relays as being stay-where-putrelays, that is, these relays will remain in their last energized position, and are polar relays. They may also be called polar two-position relays, or permanent magnet stick relays. The relays SR SRP and SR. are slow acting relays as indicated by the shaded portion at the lower end of the coil, signifying a short circuiting coil or slug, and these relays are in fact slower in dropping than they are in picking up, so that they may be said to be slow dropping relays. The relays CSA, CSB, LA LB, LA and LB are all polar relays of the non-stick three-position type, which are biased to their'neutral position. The remaining relays illustrated are relays of the neutral type, which in some cases are stick relays and in other cases do not include a stick circuit. The operating characteristics of these various relays may be somewhat difierent in order to carry out the desired operation of the system as heretofore described.

Attention is again directed to the code jumpers 50, 5| and 52 shown in Fig. 2A of the drawings, and the code jumpers I95, I96 and I9! shown in Fig. 2D of the drawings, these jumpers define the particular codes used for selecting the way station in Figs. 20 and 2D, and in registering this same way station at the central ofiice, respectively. Obviously, these code jumpers may vary in number and may be applied in various ways to obtain the 64 distinctive combinations necessary to select any one of 64 difierent way stations or register such way stations. In this connection it should be noted that four instead of three (jumpers 50, 5| and 52) could have been used in the central oflice, and it is because the fourth jumper was omitted that a zero appeared in the second station selecting period of the control cycle (see Fig. 3). For the same reason, a zero appeared in the second station registering step of the indication cycle (see Fig. 3) because no jumper was present in either the fifth or sixth jumper location of Fig. 2D, only three jumpers I95, I96 and I 91 having been employed. Also, the code jumpers 2H and 235 shown in Fig. 2B, and the code jumpers 89 and I39 shown in Fig. 2D of the drawings, illustrate how a particular way station may be selected or may be registered at the central office, providing that the code transmitted is in conformity with the code defined .by the manner in which these code jumpers are connected. As

already heretofore pointed out, there would be in the central ofiicev if the system were extended to take care of 64' way stations, 8 relays corresponding to the relay KO-l, and there wouldbe eight relays corresponding to the relay ,KO-Z for each of the relays KO I, so that there would be'a total of 64 relays corresponding to the relay KO.2.

Referring to Figs. 20 and 2D of the drawings, it will be noted that certain of the wires are shown by heavy lines. These heavy wires are only used at the last way station, and comprise part of the apparatus necessary 'to control the relays in the end battery control station (seeFig. 2D). The net result is that an intermediate station is exactly the same as the last station except for the 

